Hello!  I'm new to Phaser and HTML5 game development (but not to JS), and have been going through a few free tutorials online. I've already done the mobile toddler's game tutorial, and a simple sidescroller game tutorial, great fun so far! Today I tried to follow an infinite scolling game tutorial (not the same author and not as well written as the first two I followed), but I can't get it to work... The dog falls through the ground on collision with the fleas, and stays stuck down the